1. Field of the Invention
The present invention relates to mold release agents. More particularly, it relates to a semi-permanent water-based mold release agent.
2. Description of Related Art
Molding is a well known technique for producing finished parts made from plastics, polyester and other polymeric materials. Currently, molded parts range from bicycle helmets to boat hulls to telephone receiver handsets and beyond.
Molding is performed by processing (e.g. pouring, injecting, spraying, etc.) a liquid resin, or a reinforcing material (such as fiber reinforcing material) and a liquid resin, into a mold cavity or onto a mold surface and then curing the resin to provide a finished solid part conforming to the cavity or surface. In order to prevent the finished molded part from sticking to the mold surface, a mold release agent is applied to the surface prior to pouring the resin.
There are two basic types of mold release agent, sacrificial and semi-permanent. A sacrificial mold release agent is one that is consumed or otherwise completely depleted after a single molded part is made in the mold, and must be reapplied prior to making each molded part. For this reason, sacrificial mold release agents are costly and cumbersome to use.
Semi-permanent mold release agents are also applied to the mold surface. They can be of the wipe-on or spray-on type. These release agents are preferred because they are not completely depleted following a single molding operation. A single semi-permanent mold release agent application can be used to facilitate the release of multiple successive molded parts without reapplication of the release agent; e.g. up to 5, 10, 15, 20, 25, 30 or more releases.
Conventionally, room temperature curing semi-permanent mold release agents, e.g. for room temperature molding applications (epoxy-based or polyester-based composites), have been solvent based; that is they contain significant amounts of volatile organic compounds (VOCs), and have relatively low flash points and high vapor pressures. Existing solvent based mold release agents present significant health and safety hazards, both in use and transport.
There is a need in the art for a non-solvent based semi-permanent mold release agent, which is preferably water based, and does not suffer from the drawbacks mentioned above.